A Single Latent Plant Growth-Promoting Endophyte BH46 Enhances Houttuynia cordata Thunb. Yield and Quality.

Plant growth-promoting endophytes (PGPE) can effectively regulate plant growth and metabolism. The regulation is modulated by metabolic signals, and the resulting metabolites can have considerable effects on the plant yield and quality. Here, tissue culture Houttuynia cordata Thunb., was inoculated with Rhizobium sp. (BH46) to determine the effect of BH46 on H. cordata growth and metabolism, and elucidate associated regulatory mechanisms. The results revealed that BH46 metabolized indole-3-acetic acid and induced 1-aminocyclopropane-1-carboxylate deaminase to decrease ethylene metabolism. Host peroxidase synthesis MPK3/MPK6 genes were significantly downregulated, whereas eight genes associated with auxins, cytokinins, abscisic acid, jasmonic acid, and antioxidant enzymes were significantly upregulated. Eight genes associated with flavonoid biosynthesis were significantly upregulated, with the CPY75B1 gene regulating the production of rutin and quercitrin and the HCT gene directly regulating the production of chlorogenic acid. Therefore, BH46 influences metabolic signals in H. cordata to modulate its growth and metabolism, in turn, enhancing yield and quality of H. cordata.

Latent Pathogenic Fungi in the Medicinal Plant Houttuynia cordata Thunb. Are Modulated by Secondary Metabolites and Colonizing Microbiota Originating from Soil.

Latent pathogenic fungi (LPFs) affect plant growth, but some of them may stably colonize plants. LPFs were isolated from healthy Houttuynia cordata rhizomes to reveal this mechanism and identified as Ilyonectria liriodendri, an unidentified fungal sp., and Penicillium citrinum. Sterile H. cordata seedlings were cultivated in sterile or non-sterile soils and inoculated with the LPFs, followed by the plants' analysis. The in vitro antifungal activity of H. cordata rhizome crude extracts on LPF were determined. The effect of inoculation of sterile seedlings by LPFs on the concentrations of rhizome phenolics was evaluated. The rates of in vitro growth inhibition amongst LPFs were determined. The LPFs had a strong negative effect on H. cordata in sterile soil; microbiota in non-sterile soil eliminated such influence. There was an interactive inhibition among LPFs; the secondary metabolites also regulated their colonization in H. cordata rhizomes. LPFs changed the accumulation of phenolics in H. cordata. The results provide that colonization of LPFs in rhizomes was regulated by the colonizing microbiota of H. cordata, the secondary metabolites in the H. cordata rhizomes, and the mutual inhibition and competition between the different latent pathogens.

Endophytic fungi stimulate the concentration of medicinal secondary metabolites in houttuynia cordata thunb.

Endophytic fungi usually establish a symbiotic relationship with the host plant and affect its growth. In order to evaluate the impact of endophytic fungi on the Chinese herbal medicinal plant Houttuynia cordata Thunb., three endophytes isolated from the rhizomes of H. cordata, namely Ilyonectria liriodendra (IL), unidentified fungal sp. (UF), and Penicillium citrinum (PC), were co-cultured individually with H. cordata in sterile soil for 60 days. Analysis of the results showed that the endophytes stimulated the host plant in different ways: IL increased the growth of rhizomes and the accumulation of most of the phenolics and volatiles, UF promoted the accumulation of the medicinal compounds afzelin, decanal, 2-undecanone, and borneol without influencing host plant growth, and PC increased the fresh weight, total leaf area and height of the plants, as well as the growth of the rhizomes, but had only a small effect on the concentration of major secondary metabolites. Our results proved that the endophytic fungi had potential practical value in terms of the production of Chinese herbal medicines, having the ability to improve the yield and accumulation of medicinal metabolites.

Irpexine, an Isoindolinone Alkaloid Produced by Coculture of Endophytic Fungi, Irpex lacteus and Phaeosphaeria oryzae.

A new isoindolinone alkaloid, irpexine (1), was isolated as a racemate, along with a known green pigment, hypoxyxylerone (2), from the coculture of two endophytic fungi, Irpex lacteus and Phaeosphaeria oryzae. Compound 1 was found to be a newly produced metabolite of I. lacteus in the coculture with P. oryzae. Although 2 was produced in a monoculture of I. lacteus, its production was markedly enhanced by the coculture.

Organic Houttuynia cordata Thunb harbors higher abundance and diversity of antibiotic resistance genes than non-organic origin, suggesting a potential food safe risk.

The organic agricultural products has been growing rapidly in recent years. However, a potential food safe risk, resulted by introduction more antibiotic resistant genes (ARGs) accompanied with animal manure using to organic farming, has long been overlooked. In current study, the bacterial community, 22 tetracycline, 3 aminoglycoside and 4 ß-lactams ARGs were respectively investigated in the organic, chemical and wild Houttuynia cordata Thunb (HCT). A total of 9 tetracycline, 3 aminoglycoside and 2 ß-lactam ARG subtypes were detected, and the organic HCT harbored more ARG subtypes. The absolute and relative abundance of total ARGs in organic HCT was strikingly higher than that in chemical and wild HCT. The Enterobacteriaceae, Aeromonadaceae, Pseudomonadceae, Moraxellaceae and Oxalobacteraceae were the dominant taxa in the chemical and wild HCT, but in the organic HCT, only Enterobacteriaceae posed 83.23% - 87.40% of bacterial community. Fourteen bacterial families might be the possible hosts of ARG subtypes in the HCT. Enterobacteriaceae was a possible host of most ARG subtypes, including tetA, tetB, tetC, tetE and aadA, and it was the main bacteria affecting the behavior of ARGs in the HCT. Additionally, the tetracycline ARG subtypes had more possible hosts. These results help to better understand the ARG potential food safe risk and develop effective measures to prevent the ARG dissemination in organic agricultural product.

Lactic acid bacteria-fermented product of green tea and Houttuynia cordata leaves exerts anti-adipogenic and anti-obesity effects.

Obesity is associated with higher risks of developing diabetes and cardiovascular disease. Green tea, rich in polyphenolic compounds such as epigallocatechin gallate (EGCG) and epigallocatechin (EGC), has been shown to display anti-obesity effects. Houttuynia cordata leaves have also been shown to exhibit anti-obesity effects due to their chlorogenic acid content. Lactic acid bacteria are able to increase the production of polyphenolic compounds. This study aims to develop a novel anti-obesity fermentation product by combining H. cordata leaf tea with green tea, using Lactobacillus paracasei subsp. paracasei NTU 101 (NTU 101) for fermentation due to the advantages of bioconverting the polyphenolic compounds. The regulation of adipogenesis factors and the anti-obesity effect of the NTU 101-fermented tea were evaluated in an in vitro 3T3-L1 pre-adipocyte model and an in vivo obese rat model, respectively. The results show that the NTU 101-fermented tea, which contained higher EGCG, EGC, and chlorogenic acid levels than unfermented tea, was able to inhibit the lipogenesis of mature 3T3-L1 adipocytes by the stimulation of lipolysis. Furthermore, the body weight gain, body fat pad, and feeding efficiency of obese rats, induced with a high fat diet, were decreased by the oral administration of NTU 101-fermented tea. The significant anti-obesity effect was probably due to lipolysis. However, NTU 101 bacteria cells and EGCG may also act as functional ingredients to contribute to the anti-obesity effects of NTU 101-fermented products.

Adeninealkylresorcinol, the first alkylresorcinol tethered with nucleobase from Lasiodiplodia sp.

Adeninealkylresorcinol (1), an unusual alkylresorcinol with adenine-alkylresorcinol conjoined skeleton, was isolated from an endophytic fungus Lasiodiplodia sp. obtained from a traditional Chinese medicine Houttuynia cordata Thunb., together with three new biogenetically related compounds (2-4). Their structures were elucidated by comprehensive spectroscopic analysis, and the absolute configuration of 4 was determined by the modified Mosher's method and quantum chemical calculation. Among them, adeninealkylresorcinol (1) is the first alkylresorcinol tethered with nucleobase. In addition, the antioxidant, cytotoxic, and antimicrobial activities of 1-3 were evaluated.

Endophytic fungus strain 28 isolated from Houttuynia cordata possesses wide-spectrum antifungal activity

Abstract The aim of this paper is to identify and investigate an endophytic fungus (strain 28) that was isolated from Houttuynia cordata Thunb, a famous and widely-used Traditional Chinese Medicine. Based on morphological methods and a phylogenetic analysis of ITS sequences, this strain was identified as Chaetomium globosum. An antifungal activity bioassay demonstrated that the crude ethyl acetate (EtOAc) extracts of strain 28 had a wide antifungal spectrum and strong antimicrobial activity, particularly against Exserohilum turcicum (Pass.) Leonard et Suggs, Botrytis cinerea persoon and Botrytis cinerea Pers. ex Fr. Furthermore, the fermentation conditions, extraction method and the heat stability of antifungal substances from strain 28 were also studied. The results showed that optimal antifungal activity can be obtained with the following parameters: using potato dextrose broth (PDB) as the base culture medium, fermentation for 4–8 d (initial pH: 7.5), followed by extraction with EtOAc. The extract was stable at temperatures up to 80 °C. This is the first report on the isolation of endophytic C. globosum from H. cordata to identify potential alternative biocontrol agents that could provide new opportunities for practical applications involving H. cordata.

Endophytic fungus strain 28 isolated from Houttuynia cordata possesses wide-spectrum antifungal activity.

The aim of this paper is to identify and investigate an endophytic fungus (strain 28) that was isolated from Houttuynia cordata Thunb, a famous and widely-used Traditional Chinese Medicine. Based on morphological methods and a phylogenetic analysis of ITS sequences, this strain was identified as Chaetomium globosum. An antifungal activity bioassay demonstrated that the crude ethyl acetate (EtOAc) extracts of strain 28 had a wide antifungal spectrum and strong antimicrobial activity, particularly against Exserohilum turcicum (Pass.) Leonard et Suggs, Botrytis cinerea persoon and Botrytis cinerea Pers. ex Fr. Furthermore, the fermentation conditions, extraction method and the heat stability of antifungal substances from strain 28 were also studied. The results showed that optimal antifungal activity can be obtained with the following parameters: using potato dextrose broth (PDB) as the base culture medium, fermentation for 4-8d (initial pH: 7.5), followed by extraction with EtOAc. The extract was stable at temperatures up to 80°C. This is the first report on the isolation of endophytic C. globosum from H. cordata to identify potential alternative biocontrol agents that could provide new opportunities for practical applications involving H. cordata.

[Correlation analysis of nutrients and microorganisms in soils with polyphenols and total flavonoids of Houttuynia cordata].

The relationship of nutrients and microorganisms in soils with polyphenols and total flavonoids of Houttuynia cordata were investigated by measuring nutrients, enzyme activity, pH, concentrations of microbe phospholipid fatty acids (PLFAs) in soils, and determining concentrations of polyphenols and total flavonoids of H. cordata. The research is aimed to understand characteristics of the planting soils and improve the quality of cultivated H. cordata. The soils at different sample sites varied greatly in nutrients, enzyme activity, pH, microbic PLFAs and polyphenols and all flavonoids. The content of total PLFAs in sample sites was following: bacteria > fungi > actinomyces > nematode. The content of bacteria PLFAs was 37.5%-65.0% at different sample sites. Activities of polyphenol oxidease, concentrations of available P and content of PLFAs of bacteria, actinomyces and total microorganisms in soils were significantly and positively related to the concentrations of polyphenols and total flavonoids of H. cordata, respectively (P < 0.05) . The Content of fungi PLFAs in soils was significantly and negatively related to concentrations of polyphenols and total flavonoids of H. cordata, respectively (P < 0.05). This study provides evidence that effectiveness of the soil nutrient, which may be improved due to transformation of soil microorganisms and enzymes to N and P in the soils, was beneficial to adaptation of H. cordata adapted to different soil conditions, and significantly affects metabolic accumulation of polyphenols and flavonoids of H. cordata.

Antimicrobial activity of secondary metabolites from Streptomyces sp. K15, an endophyte in Houttuynia cordata Thunb.

We isolated Streptomyces sp. K15 from the root tissue of Houttuynia cordata Thunb and found that some of its secondary metabolites exhibited significant antimicrobial activity against Botrytis cinerea. Moreover, we separated, purified and identified the major active ingredient to be 2-pyrrol formic acid by using silica gel column chromatography, high-performance liquid chromatography and NMR analysis of the spectral data. 2-Pyrrol formic acid critically inhibited the growth of some phytopathogenic bacteria. Therefore, it has potential value in agricultural applications.

Phytohabitans flavus sp. nov., Phytohabitans rumicis sp. nov. and Phytohabitans houttuyneae sp. nov., isolated from plant roots, and emended description of the genus Phytohabitans.

An actinomycete strain, designated K09-0627(T), was isolated from the roots of an orchid collected in Okinawa Prefecture, Japan. Two actinomycete strains K11-0047(T) and K11-0057(T) were isolated from the roots of Rumex acetosa and Houttuynia cordata collected in Kanagawa Prefecture, Japan. 16S rRNA gene sequence analyses indicated that the isolates belonged to the genus Phytohabitans, and that they were closely related to each other and to Phytohabitans suffuscus K07-0523(T). The DNA-DNA relatedness values between the three isolates and Phytohabitans suffuscus were below 70%. On the basis of phylogenetic analysis, DNA-DNA relatedness values and phenotypic characteristics, the strains should be classified as novel species in the genus Phytohabitans, for which the names Phytohabitans flavus sp. nov. (type strain, K09-0627(T)=JCM 17387(T)=NBRC 107702(T)=DSM 45551(T)), Phytohabitans rumicis sp. nov. (type strain, K11-0047(T)=JCM 17829(T)=NBRC 108638(T)=BCC 48146(T)) and Phytohabitans houttuyneae sp. nov. (type strain, K11-0057(T)=JCM 17830(T)=NBRC 108639(T)=BCC 48147(T)) are proposed.

[Transformation of antimicrobial peptide fusion gene of cecropin B and rabbit NP-1 to Houttuynia cordata].

OBJECTIVE: To transform the antimicrobial peptide fusion gene of cecropin B and rabbit NP-1(CN) into Houttuynia cordata to improve its antimicrobic capability. METHOD: The fusion gene of CN designed and synthesized artificially was recombined with expression vector pBI121. The recombined vector was transformed to Agrobacterium tumefaciens LBA4404, by which CN gene was transformed to the explants of H. cordata. The transgenic regeneration plantlets were selected by kanamycin and rapid screening PCR. The transgenic plants were identified by PCR-Southern of genomic DNA and RT-PCR. The disease resistances were detected by antibacterial zone trail of leaf extracts to E. coli K12 and infection by Rhizoctonia solani. RESULT: Gene of interesting CN was inserted into genomic DNA and expressed in transformed H, cordata, whose resistance to E. coli K12 and Rh. solani was stronger than that of the non-transformed control. CONCLUSION: The fusion gene CN can improve antimicrobic capability of transformed H. cordata.